Typically, a fluid such as a silicone elastomer or a polyester is introduced to the component to be potted such that the component is enveloped in the potting compound. The potting compound is then allowed to cure to form a solid around and, possibly, within the component. Excess potting material can then be removed as required.
In particular, the present invention relates to potting a component that will be subject to high electric field strengths in use. For example, electrical or electronic devices or parts thereof are often potted in a dielectric material, i.e. the potting compound then forms a dielectric between conducting components. This is advantageous because the potting compound usually offers greater resistance to electrical breakdown when exposed to high electrical fields than merely leaving an air-gap between conducting components. In addition, the potting compound may offer some structural support.
However, known potting compounds have only limited capability as dielectrics because their electrical breakdown value is too low for use at high voltages. Although polymers used as potting compounds have typical intrinsic electrical breakdown values of 10–100 kV/mm, this value is not reflected in the potting compound when cured due to the presence of air-filled voids. The onset of breakdown in these voids is quicker due to the far lower electrical breakdown value of air and, worse still, it is thought that formation of breakdown streamers in the voids initiates breakdown in the potting compound itself. Hence, the insulating capability of known potting compounds is greatly diminished.